This invention relates generally to catheters, specifically to endotracheal suction catheters, particularly of that class that are sterile, self-contained, and lubricated. The specific invention is of a form of such a catheter that, in use, significantly reduces the risk of segmental atelectasis distal to the catheter, and thus, significantly reduces the risk of trauma induced pneumonia in a patient.
In general, such a catheter is used on a postoperative, respiratory compromised, comatose, or anesthetized patient for suctioning liquid secretions which may occur within the bronchial system of the lungs. Such an application is usually a procedure performed in conjunction with other actions to maintain and restore proper breathing and oxygenation within this type patient.
The application of suction through a catheter within the bronchial system poses a constant risk of suction clamping of the catheter to the mucosa, with resulting trauma to the bronchial mucosal structure and the probability of swelling and/or bleeding occurring, increasing the risk of pneumonia. A more serious danger occurs because of the swelling of the mucosa and consequent restriction in the bronchial passageways incident to those medical conditions requiring the use of catheter suction to clear liquid from the lungs. The restricted bronchial passages raise a constant risk that an excessive insertion of the catheter will block the bronchia; and the suction will then collapse entirely that portion of the bronchial tree sealed off by the over-insertion of the catheter. Such a collapse is generally irreversible; the resulting segmental atelectasis results in reduction of the breathing capacity of the lung, subsequent pneumonia, and creates a high risk of mortality in the compromised patient.
The prevention of such segmental atelectasis during catheter use has been based on the skill of the treating medical personnel who, by estimate and experience, judge distance of insertion of the catheter. This cannot positively prevent the possibility of contact of the catheter with a mucosa and lining of the bronchial tubes.
The possibility of mucosal ingestion, with resulting trauma, by the suction apertures of the catheter has been recognized, and various forms of shielded drainage orifices have been developed to prevent or ameliorate this particular effect. Such prior developments include Lomholt, U.S. Pat. No. 4,227,529, which discloses a structure to reduce clamping of the catheter to the mucosa by suction and reduces the effect of mucosal damage. Earlier structures for shielded drainage orifices include Ericson, U.S. Pat. No. 3,435,827, and Beall, U.S. Pat. No. 3,136,316.
An inflatable cuff may be installed upon an endotracheal catheter to provide a tight seal at the entrance to the bronchial tree; the use of such an inflatable cuff is well known to prevent ingestion or passage of vomitus or fluid contaminate into the lungs of an anesthetized patient. A similar structure shown in Wallace, U.S. Pat. No. 2,749,913.